Backyard Astronomy: Study Uncovers 12 Nearby Stars
- By Robert Roy Britt Senior Science Writer 01/01/2002

WASHINGTON D.C. - With astronomers finding galaxies that are billions of light-years away and spotting stars thousands of light-years distant in our own galaxy, you'd think they'd know about all the stars in our backyard.
Not so. Today, researchers announced a dozen newly found stars all within 33 light-years of Earth -- next-door neighbors by cosmic measures. All the stars were found in the southern sky, where surveys are less comprehensive than from the Northern Hemisphere.

The discoveries were made by a team of researchers led by Todd Henry of Georgia State University. Henry and his colleagues are working to build a 3-D map of the local sky.

The nearest known star is Proxima Centauri, which is 4.2 light-years away. The nearest of the newly discovered objects is 20 light-years away, putting it at 55th on the list of closest stars.

The stars come in three configurations: Seven are alone in space; two orbit each other in what's called a binary star system; and the remaining three are in a rarer three-star system, all orbiting each other.

All had gone unseen because they are thousands of times fainter than stars that can be seen with the naked eye. The nearest one is only about a third of the size of the Sun and emits less than 1 percent as much light.

One of the stars is a white dwarf. The others are red dwarfs.

Red dwarfs are sometimes counted as part of "dark matter," somewhat mysterious material that can't be seen but that researchers know must exist based on the amount of gravity at work in galaxies.

White dwarf stars are typically about the size of Earth, but they can be as massive as the Sun. That makes them dense. A teaspoonful of a white dwarf weighs as much as an elephant. White dwarf stars are the end of the evolutionary road for smallish stars, ones that could not generate the spectacular explosions that mark the death of larger stars.

Because of their proximity, the newly identified stars could prove useful as targets for planet hunters.
"Each of the new stars provides a fresh target where we can look for planets, and ultimately, for life on those planets," Henry said here at a meeting of the American Astronomical Society.

The stars were studied with two telescopes at the Cerro Tololo Interamerican Observatory in Chile. The research team included Georgia State's Wei-Chun Jao and John Subasavage; Phil Ianna of the University of Virginia; Rene Mendes of the European Southern Observatory; and Edgardo Costa of the Universidad de Chile.

Full Coverage of the 2002 AAS Meeting